Automatic firearm



H. W. GABBETT-FAIRFAX.

AUTOMATIC FIREARM.

APPLICATION FILED APR. 5, 1920.

1 44,499 Patented June 22, 1920.

2 SHEETS-SHEET l.

H. W. GABBETT-FAIRFAX.

AUTOMATIC FIREARM.

APPLICATION FILED APR. 5. 1920.

2 SHEETS-SHEET Patented. June 22, 1920.

qggi$di 6 nuen WILLIAM. GABBETT-FAIRFAX, or ennon, ENGLAN AUTOMATIC FIREARM.

Application filed April 5, 1920s Serial No. 371,546.

To all whom it may concern:

Be it known that I, HUGH WILLIArr GAB- BETT-FAIRFAX, a subject of the King of Great Britain, residing at London, England, have invented new and useful Improvements in Automatic Firearms, of which the following is a specification.

This invention relates to automatlc machine guns and small arms in which the breech mechanism is operated by compressed air or compressible fluid.

According to my present invention I utilize the energy developed onfiring the gun to compress air or other compressible fluid and store it in a receiver or receivers attached to the gun mounting or to the gun, as may bemost convenient, from which receiver or receivers the air or fluid is taken as required for operating the gun. The energy required to compress the air or other fluid is obtained according to one arrangement by the recoil movement of the barrel, and according to another arrangement by a sliding or rotary muzzle cap. These two arrangements may be combined in cases where either the energy of recoil or the energy obtainable from the muzzle cap 1s 1nsufiicient or barely sufiicient of itself to operate the gun, or in which it is desirable to increase the rate of fire obtainable by the use of either arrangement separately. The release of the compressed fluid to allow 1t to perform the desired work is effected by the movement of the recoiling parts, or of the muzzle cap. as the case may be, such release taking place during recoil, or just at the completion of the recoil, or after the recoiling parts have begun to move forward When the two methods are used together, the air or fluid compressed by the'action of the muzzle cap may be .made to operate in conjunction with that compressed by the recoil for performing all the functions necessary to the operation of the gun,-a common receiver being used for the air compressed by both methods, or the muzzle cap system may be used to compress the fiu1d and store it in a separatereceiver to perform such of the functions as may be most suitable, the remaining functions being performed by the recoil system.

In the accompanying drawings which illustratethe two methods combined Figures 1- and 1, read together, are a longitudinal section illustrating one arrangement of mechanism with a single recelver constructed according to my present invention.

Elgs. 2 and 2, read together, are a longitudmal section illustrating a modified arrangement in which there are two receivers, one controlled bythe recoil system and the other by the muzzle cap system.

Referrlng to Fig. 1, I use a muzzle cap l3, sl1d1ng on the gun barrel A, the cap hav- 1ng a blast cavity G at its forward end, against the walls of which the blast gases implnge as they issue from the muzzle.

The cap B is connected by the link D plvoted lever E, and link F to an air compfessing plston Gr which works in a c linder The pivot on whichcthe link turns is carried by the gun frame S. B is a spring for returning the muzzle cap to its orlgmal position when the blast gases have escaped.

To the barrel A (or to some part fixed to the barrel) is rigidly attached an arm Q which is connected b a link C to an air compressing piston which works in a cylinder H.

' The two cylinders H and H communicate with a receiver N by pipes D, D, a nonreturn valve K being provided toprevent the return of compressed air from the receiver to the cylinders. There may be a separate non-return valve for each cylinder if found desirable.

The receiver N= communicates with an action cylinder J through a pipe P in which there is a timing valve P. This valve is controlled by a rod R connected to the arm 0 and furnished with tappets R, R for actuating the arm P of the valve. In one position of the valve the receiver Nis laced in communication with the action cy inder J, and in another position the action cylinder is placed in communication with the external atmosphere through an exhaust opening 1 p The piston crates the breech mechanism in a known manner. L is a spring for returning the action piston and closing the breech. The two cylinders H, H, the receiver N and J of the action cylinder op- Specification of Letters Iatent. te m 22, 2

the action cylinder J are all carried py muzzle impinge against the front wall of the blast cavity C in the muzzle cap B,

and carry the cap forward, compressing the spring B, and acting through the link D lever E and link F on the piston G driving it backward and compressing the air in the cylinder H.

At the same time the barrel recoils and drives back the piston G compressing the air in the cylinder H. The air so compressed in the cylinders H and H passes be 0nd the valve K into the receiver N.

he muzzle cap is long enough, as shown, to permit of a forward travel equal to the stroke of the piston G, and a corresponding recoil of the barrel of like amount.

It should be noted that at the beginning of each stroke the air in the cylinders should be at atmospheric pressure, suitable measures being adopted to recharge the cylinders from the atmosphere. Any well known device for doin this may be adopted, for example holes IP, H in the cylinder walls may be uncovered by the pistons G, Gr at the end of their forward stroke.

, About the end of the recoil, the timing valve P is opened by the rod R and the compressed air from the receiver is thereby admitted to the action cylinder J whereupon the piston J is driven back against the action of its spring L, opens the breech and extracts the spent cartridge.

The barrel and muzzle cap ,meanwhilev return to their original positions, and the timing valve is thereby set to exhaust (the position shown in the drawing) whereupon the spring L-of; the action piston operates to close the breech, the ejection having been performed by the movement of the bolt.

Another cylinder charged from the receiver may be provided for operating the cartridge feed mechanism, or the feed may be operated mechanically.

In the 'modification illustrated in Fig. 2, the muzzle cap B is of the type in which the gases escape through outlets in the barrel. The muzzle cap B is shown directly connected to the air compressing piston Gr' by an arm B fixed to or formed on the Inuzzle cap.

In this arrangement I have shown two independent receivers N N forthe compressed air, the receiver N being supplied by'the recoil actuated piston G, and thereceiver N being kept supplied by the muzzle cap actuated piston G. K and K are nonreturn valves to prevent return of compressed air to the compression cylinders. The outlet P from the receiver N is :Eu'rnished with a timing valve P controlled through a rod R by the recoil arm C as in the arrangement shown in Fig.1, and the outlet 1? from the receiver N is also provided with a timing valve P of similar construction controlled by a rod R from the muzzle cap arm B These outlets are shown communicating with a common pipe V leading to the action cylinder J. The pipes P and I which communicate with the common pipe V are shown provided with taps P P each tap being placed between the T junction 1" and its respective timing valve, so that should either system break down its respective receiver may be com letely shut off from the action cylinder J and from the other receiver, thus making it possible for the gun to go on firing under the control of the remalnin-g system. Each valve has an on position and an exhaust position, but if desired it may also have an off position.- It is obvious that the compressed fluid from the two receivers may be used for performing separate functions, if desired.

In the arrangements shown any one piston or all the pistons may be arranged to be returned to their original positions by means of compressed air, or other compressible fluid, instead of by springs. Moreover the action piston moves back for a distance equal to that through which the .barrel recoils and further movement of the action piston which is necessary for the unlocking of the breech and retraction of the bolt is caused by the action of thecompressed air.

The compression cylinders are furnished with holes H corresponding to those in the compression cylinders in Fig. 1.

I claim o 1. In an automatic firearm, a fluid compressing cylinder and piston, means operated by the explosion gases for moving said cylinder and piston relatively to each other, a second fluid compressing means operated by the recoil movement of the gun, a receiver in which the fluid compressed in said cylinders is stored, and means automatically operated by the recoil and counter-recoil movements of the gun for taking the fluid from the receiver as required to work the gun.

2. In an automatic firearm, a fluid. compressing cylinder and piston, a positive conneetion between said piston and the gun for moving said piston relatively to said cylinder during the recoil movement of the. gun, a receiver in which the fluid compressed in said cylinder is stored, and means including a -valve and a rod 'operated by saidconnection having spaced tappets for controlling said valve and taking the fluid from the re ton are moved relatively to each other by said muzzle-cap, an independent receiver for the compressed fluid from each cylinder, and

means for taking the compressed fluid from 15 the receivers for operating parts of the gun. Dated this eleventh day of March, 1920.

HUGH WILLIAM 'GABBETT-FAIRFAX.

Witnesses:

H. N. ADAMS CAPPER, GEORGE H. Gr. SHEPHERD. 

